commit ed9f87c90119832c3c96fb9c352e53db61943fe4
author Valentin Bartenev <vbart@nginx.com> Fri Apr 12 15:02:33 2013 +0000
committer Valentin Bartenev <vbart@nginx.com> Fri Apr 12 15:02:33 2013 +0000
tree 4feedf5c7c969c4f45aa2d367b974cb81e97f00f
parent 7a7650aeb16ee21a5f596cd855c97066726c00a8

Events: protection from stale events in eventport and devpoll.

Stale write event may happen if read and write events was reported both,
and processing of the read event closed descriptor.

In practice this might result in "sendfilev() failed (134: ..." or
"writev() failed (134: ..." errors when switching to next upstream server.

See report here:
http://mailman.nginx.org/pipermail/nginx/2013-April/038421.html

src/event/modules/ngx_devpoll_module.c

diff --git a/src/event/modules/ngx_devpoll_module.c b/src/event/modules/ngx_devpoll_module.c
index d09b5bc..5f78cd7 100644
--- a/src/event/modules/ngx_devpoll_module.c
+++ b/src/event/modules/ngx_devpoll_module.c
@@ -343,7 +343,7 @@
     ngx_fd_t            fd;
     ngx_err_t           err;
     ngx_int_t           i;
-    ngx_uint_t          level;
+    ngx_uint_t          level, instance;
     ngx_event_t        *rev, *wev, **queue;
     ngx_connection_t   *c;
     struct pollfd       pfd;
@@ -510,7 +510,13 @@
                 ngx_locked_post_event(rev, queue);
 
             } else {
+                instance = rev->instance;
+
                 rev->handler(rev);
+
+                if (c->fd == -1 || wev->instance != instance) {
+                    continue;
+                }
             }
         }
 

src/event/modules/ngx_eventport_module.c

diff --git a/src/event/modules/ngx_eventport_module.c b/src/event/modules/ngx_eventport_module.c
index d6dcb0b..5f9cf4e 100644
--- a/src/event/modules/ngx_eventport_module.c
+++ b/src/event/modules/ngx_eventport_module.c
@@ -551,7 +551,7 @@
                 } else {
                     rev->handler(rev);
 
-                    if (ev->closed) {
+                    if (ev->closed || ev->instance != instance) {
                         continue;
                     }
                 }